As is known in the art, one type of conventional current sensor uses a Hall effect element, which generates a voltage in response to a magnetic field associated with a current passing through a conductor. Typical current sensors of this type include a Hall effect element mounted on a dielectric material, for example a circuit board. In some applications, a ferrous core (magnetic flux concentrator) is used in proximity to the Hall effect element.
Another type of current sensor uses a magnetoresistance element, which changes resistance in response to a magnetic field associated with a current passing through a conductor. A fixed electrical current is directed through the magnetoresistance element, thereby generating a voltage output signal proportional to the magnetic field. Some conventional current sensors of this type use an anisotropic magnetoresistance (AMR) element mounted on a dielectric material, for example a circuit board.
Various parameters characterize the performance of current sensors, including sensitivity and linearity. Sensitivity is related to a change in the resistance of the magnetoresistance element or a change in output voltage from the Hall effect element in response to a change in magnetic field. Linearity is related to the degree to which the resistance of the magnetoresistance element or the output voltage from the Hall effect element varies in direct linear proportion to the magnetic field.
Another parameter that can characterize a current sensor is an ability to withstand at least a predetermined breakdown voltage between the current sensor and a conductor near which the current sensor is disposed in order to measure a current in the conductor.
There can be a tradeoff between current sensor sensitivity and the above-described breakdown voltage. Namely, in order to achieve high sensitivity, it is desirable that the current sensor, and, in particular, a current (magnetic field) sensing element within the current sensor, be disposed proximate to and as close to the conductor as possible. However, close proximity tends to reduce the breakdown voltage.
Various types of magnetic field sensing elements (e.g., Hall effect elements and magnetoresistance elements), which are used in current sensors, are known to have different characteristics, including, but not limited to, different sensitivities, different linearities, and also different hysteresis characteristics in response to a magnetic field. It is also known that many types of magnetoresistance elements have a higher sensitivity than a Hall effect element. It is also known that a particular type of magnetic field sensing element, for example, a Hall effect element, can have a substantially different sensitivity when the substrate (i.e., sensitive layer) is comprised of different materials, for example, Silicon (Si) and Gallium Arsenide (GaAs).
It would be desirable to provide a current sensor having a both a relatively high sensitivity and also a relatively high breakdown voltage.